Figured out the problem need a soulution for m16/m4 hop up chamber

[2nd battalion 2LT]

Alright ..after a mostly smooth build up I am at the end ..putting the upper to the lower ...making last checks on fitment ..it seems with my jg body .. that my new metal g&p hop up is slighty bigger then the plastic one .this is causing the mag catch to not catch the mag when inserted ..

What I am looking for is a hop up chamber preferebly metal that is in spec with the jg one ..other wise ..is it really a con to use a plastic hop up chamber ?